October 2010
Surface Water Supply Index Report

Provided by the US Natural Resources Conservation Service
Bozeman, Montana

The SWSI is designed for areas that rely primarily on snowmelt runoff as the primary source of surface water. The SWSI accounts for snowpack, mountain precipitation, streamflow, reservoir contents, and soil moisture conditions. The SWSI can be used by irrigators, fisheries personnel, recreationists, and others who utilize surface waters. SWSI values are categorized as follows:

IDBasin NameValue
1Marias Above Tiber Reservoir0.6
1Marias Above Tiber Reservoir0.6
2Tobacco3.5
2Tobacco3.5
3Kootenai to Libby Dam2.2
3Kootenai to Libby Dam2.2
4Kootenai River below Libby Dam-0.7
4Kootenai River below Libby Dam-0.7
5Fisher River0.1
5Fisher River0.1
6Yaak River3.2
6Yaak River3.2
7North FK. Flathead River3.2
7North FK. Flathead River3.2
8Middle FK. Flathead River2.1
8Middle FK. Flathead River2.1
9South FK. Flathead River0.8
9South FK. Flathead River0.8
10Flathead at Columbia Falls1
10Flathead at Columbia Falls1
12Swan River3.1
12Swan River3.1
13Flathead River at Polson2.5
13Flathead River at Polson2.5
14Mission Valley0
14Mission Valley0
15Little Bitterroot River0
15Little Bitterroot River0
16Clark above Missoula3
16Clark above Missoula3
17Blackfoot River-0.2
17Blackfoot River-0.2
18Clark Fork above Missoula1.9
18Clark Fork above Missoula1.9
19Bitterroot River0.6
19Bitterroot River0.6
20Clark Fork River below Bitterroot River1.5
20Clark Fork River below Bitterroot River1.5
21Clark Fork River below Flathead River2.1
21Clark Fork River below Flathead River2.1
22Beaverhead River2.9
22Beaverhead River2.9
23Ruby River2
23Ruby River2
24Big Hole River2.5
24Big Hole River2.5
25Boulder River (Jefferson)3.2
25Boulder River (Jefferson)3.2
26Jefferson River2.4
26Jefferson River2.4
27Madison River-1.6
27Madison River-1.6
28Gallatin River1.5
28Gallatin River1.5
29Missouri River above Canyon Ferry1.2
29Missouri River above Canyon Ferry1.2
30Missouri River below Canyon Ferry1.5
30Missouri River below Canyon Ferry1.5
31Smith River3.5
31Smith River3.5
32Sun River-1.6
32Sun River-1.6
33Teton River0.2
33Teton River0.2
34Birch/Dupuyer0.2
34Birch/Dupuyer0.2
35Marias Below Tiber Reservoir2.4
35Marias Below Tiber Reservoir2.4
36Musselshell River3.7
36Musselshell River3.7
37Missouri River above Fort Peck1.7
37Missouri River above Fort Peck1.7
38Missouri River below Fort Peck0.1
38Missouri River below Fort Peck0.1
39Milk River3.3
39Milk River3.3
40Dearborn1.9
40Dearborn1.9
41Yellowstone River above Livingston-0.3
41Yellowstone River above Livingston-0.3
42Shields River3.7
42Shields River3.7
43Boulder River (Yellowstone)2.7
43Boulder River (Yellowstone)2.7
44Stillwater River0
44Stillwater River0
45Rock/Red Lodge Creeks1.5
45Rock/Red Lodge Creeks1.5
46Clarks Fork River-1.2
46Clarks Fork River-1.2
47Yellowstone River above Bighorn River-0.1
47Yellowstone River above Bighorn River-0.1
48Bighorn River below Bighorn Lake-0.2
48Bighorn River below Bighorn Lake-0.2
49Little Bighorn River1.3
49Little Bighorn River1.3
50Yellowstone River below Bighorn River-0.1
50Yellowstone River below Bighorn River-0.1
51Tongue River3.7
51Tongue River3.7
52Powder River-1
52Powder River-1
53Upper Judith River3.9
53Upper Judith River3.9
54Saint Mary River4
54Saint Mary River4